It is possible that skb is freed in ath9k_htc_rx_msg(), then
usb_submit_urb() fails and we try to free skb again. It causes
use-after-free bug. Moreover, if alloc_skb() fails, urb->context becomes
NULL but rx_buf is not freed and there can be a memory leak.
The patch removes unnecessary nskb and makes skb processing more clear: it
is supposed that ath9k_htc_rx_msg() either frees old skb or passes its
managing to another callback function.
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
Fixes: 3deff76095c4 ("ath9k_htc: Increase URB count for REG_IN pipe")
Signed-off-by: Fedor Pchelkin <pchelkin@xxxxxxxxx>
Signed-off-by: Alexey Khoroshilov <khoroshilov@xxxxxxxxx>
---
v1->v2: add comment about freeing an skb and remove double blank line
drivers/net/wireless/ath/ath9k/hif_usb.c | 28 +++++++++++++-----------
1 file changed, 15 insertions(+), 13 deletions(-)
diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
index 4d9002a9d082..401b408cb7a4 100644
--- a/drivers/net/wireless/ath/ath9k/hif_usb.c
+++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
@@ -708,14 +708,13 @@ static void ath9k_hif_usb_reg_in_cb(struct urb *urb)
struct rx_buf *rx_buf = (struct rx_buf *)urb->context;
struct hif_device_usb *hif_dev = rx_buf->hif_dev;
struct sk_buff *skb = rx_buf->skb;
- struct sk_buff *nskb;
int ret;
if (!skb)
return;
if (!hif_dev)
- goto free;
+ goto free_skb;
switch (urb->status) {
case 0:
@@ -724,7 +723,7 @@ static void ath9k_hif_usb_reg_in_cb(struct urb *urb)
case -ECONNRESET:
case -ENODEV:
case -ESHUTDOWN:
- goto free;
+ goto free_skb;
default:
skb_reset_tail_pointer(skb);
skb_trim(skb, 0);
@@ -735,25 +734,27 @@ static void ath9k_hif_usb_reg_in_cb(struct urb *urb)
if (likely(urb->actual_length != 0)) {
skb_put(skb, urb->actual_length);
- /* Process the command first */
+ /*
+ * Process the command first.
+ * skb is either freed here or passed to be
+ * managed to another callback function.
+ */
ath9k_htc_rx_msg(hif_dev->htc_handle, skb,
skb->len, USB_REG_IN_PIPE);
-
- nskb = alloc_skb(MAX_REG_IN_BUF_SIZE, GFP_ATOMIC);
- if (!nskb) {
+ skb = alloc_skb(MAX_REG_IN_BUF_SIZE, GFP_ATOMIC);
+ if (!skb) {
dev_err(&hif_dev->udev->dev,
"ath9k_htc: REG_IN memory allocation failure\n");
- urb->context = NULL;
- return;
+ goto free_rx_buf;
}
- rx_buf->skb = nskb;
+ rx_buf->skb = skb;
usb_fill_int_urb(urb, hif_dev->udev,
usb_rcvintpipe(hif_dev->udev,
USB_REG_IN_PIPE),
- nskb->data, MAX_REG_IN_BUF_SIZE,
+ skb->data, MAX_REG_IN_BUF_SIZE,
ath9k_hif_usb_reg_in_cb, rx_buf, 1);
}
@@ -762,12 +763,13 @@ static void ath9k_hif_usb_reg_in_cb(struct urb *urb)
ret = usb_submit_urb(urb, GFP_ATOMIC);
if (ret) {
usb_unanchor_urb(urb);
- goto free;
+ goto free_skb;
}
return;
-free:
+free_skb:
kfree_skb(skb);
+free_rx_buf:
kfree(rx_buf);
urb->context = NULL;
}
--
2.25.1
